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Lake Core Biomarkers, 2015-2020. Supported by NSF BCS-1623368.
PI Elizabeth Arkush, Co-PIs Aubrey Hillman, Mark Abbott and Joseph Werne.
This collaborative project took sediment cores from three lakes in the Peruvian Titicaca basin, and analyzed sedimentology, isotope ratios and organic geochemistry, including fecal biomarkers (5β-stanols) from humans and camelids, to arrive at a picture of paleoclimate and changing populations through time.
In 2015, a crew led by Dr. Hillman obtained sediment cores from Laguna Arapa, Laguna Orurillo, and Laguna Umayo (left, red squares). Additional sediment and plant samples were obtained in 2017.
The Orurillo core was particularly informative. Subsequent lab analysis led by Aubrey Hillman and Elliot Arnold identified human and camelid organic stanols and reconstructed precipitation levels from this core.
In combination, our results show, first, a phase of severe aridity corresponding with the Medieval Climatic Anomaly (MCA), in agreement with other regional climate proxies; and second, changing levels of camelid populations as a ratio with human populations, which appear to be correlated with both environmental and social factors.
Results are published in Arnold et al. (2021, Fecal stanol ratios, QSR) and Arnold et al. (2021, Drought, QSR).
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